Unsure about this sibset...

As usual, I got this idea for a story with a sibset of 4 to name, and I got stuck. They are 2 girls and a boy, the older girl is 12, the middle one is 9 or 8, then there's the 6-year-old boy and a newborn/1-y-o girl at last. The boy could be either Peter or Gabriel (kinda weird to use one of them as a middle name for the other!), while I thought something classical for the older girls, like Charlotte, Adele, Lydia or Elizabeth. For the youngest, I came up with Greta, but I don't like it's alliteration with Gabriel -which is probably going to be the final choice, but I could get over the same initials thing, since I love the names- nor the fact that it sounds slightly less feminine than the others. Also, most of these names have A-E vowels, and I wanted to use that as a subtle connection, but in that case Lydia would be out. If you add the R to this trend, then Adele would be out too, and I'm one name short.
The final draft has Adele, Charlotte, Gabriel and Greta penciled in, but I'm still unsure about this set. Plus, middle names are still a mystery. I might as well go ahead and avoid them altogether. Would it be weird?

Any suggestions? Even if they don't fit with the A-E-R trend, add them, I might just get inspired!

Irene; Name lover in her twenties; single; Languages student by day, writer by night.

“I read books when I was a kid, lots of books. Books always seemed like magic to me. They took you to the most amazing places. When I got older, I realized I couldn't find books that took me to all the places I wanted to go. To go to those places, I had to write some books myself.”
― Pat Murphy, The Wild Girls

"Like everyone else, I am going to die. But the words – the words live on..."
― J. Michael Straczynski